Socket InputStream on windows blocks and swaps que

Question

I'm writing a simple ServerSocket program and connecting to it from two browser tabs by urls: http://127.0.0.1:8080/Q1 and after a 10 sec pause http://127.0.0.1:8080/Q2.

My problem is that on ubuntu18 machine with java10 it works quick and fine. But on two win machines (my win8.1 with java8 and other win10 with java11) it hangs up after first query and does nothing for up to 2 minutes, server stays quiet if I don't send second query. If I send second query I get result for both queries (in swaped order first Q2 then Q1) in browser and my server reports reading both queries and next two browser does for favicons (swaped too - first Q2 then Q1 in 90% cases).

And if I just wait after starting Q1 (without starting Q2), first I see Socket#1 is created and it waits. It waits for 2 minutes and closes. Then in a moment server creates #2 sockets and quickly answers on Q1, closes, creates #3 socket gets and answers Q1-favicon query, that browser sent. All done very fast and beautiful. I would like not to have this pause with #1 Socket. I don't have it on ubuntu18 machine.

What am I doing wrong? Or is it something wrong with my win machines? Does your win machines process first query without waiting for second query?

import java.io.PrintWriter;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.InputStreamReader;
import java.io.BufferedReader;
import java.net.Socket;
import java.net.ServerSocket;
import java.util.stream.Collectors;
import java.io.IOException;

public class localhost {
    public static void main(String[] args) {
        int portNumber = 8080;
        System.out.println("Started...");
        String s="#";
        String ans="#";
        try (
        ServerSocket serverSocket = new ServerSocket(portNumber)){
            String httpResponse;
            int i=0;
            while(true){
                i++;
                System.out.println("Creating new Clien Socket #"+i);
                try( Socket clientSocket = serverSocket.accept()){
                    System.out.println("Accepted... "+clientSocket.toString());
                    try(InputStream in=clientSocket.getInputStream();){
                        {byte[] buffer = new byte[10000];
                        int total = in.read(buffer);
                        if (total>0) {
                            s = new String(java.util.Arrays.copyOfRange(buffer, 0, total));
                            System.out.println(s);

                            httpResponse = "HTTP/1.1 200 OK\r\n\r\nHello, there, "+ s.substring(5,7) +"!";
                            OutputStream out=clientSocket.getOutputStream();
                            out.write(httpResponse.getBytes());
                        } else { System.out.println("Empty..."); }
                        System.out.println("Finished #"+i+" "+clientSocket.toString());
                        System.out.println();}
                    }
                }
            }

        } catch(Exception e){
            System.out.println("Error: "+e);
        }
        System.out.println("I'm done "+s);
    }
}

UPD: For Q1 without Q2 case if I'm getting it right Wireshark shows two sockets - 50410 and 50411, while server accept()-ed only one - 50411. Looks like 50410 causes waiting, what is this empty query and where is it coming from?

Answer 1

In a similar question I found a useful link saying it may be caused by "Predict network actions to improve page load performance" setting. So I tried turning off prediction settings one by one and it worked. In chrome version 73.0.3683.86 (Official Build) (64-bit) this behavior was caused by chrome setting "Use a prediction service to load pages more quickly" turned on.

So in just go to setting -> advanced -> privacy and security -> Use a prediction service to load pages more quickly and turn it OFF. (Or, if you don't have it in your chrome version, try turning off similar settings ).